High- frequency semiconductor device and method of manufacturing the same

ABSTRACT

The object of the present invention is to implement an enhancement in a noise eliminating characteristic of a wiring compatibly with promotion of microfabrication and simplification of a manufacturing process. Upper and side surfaces of a wiring ( 6 ) for transmitting a signal are continuously covered by a conductor layer ( 12 ) with insulators ( 7 ), ( 8 ) and ( 9 ) interposed therebetween in a section crossing a direction of extension thereof, and the conductor layer ( 12 ) is connected to a semiconductor substrate ( 1 ). Moreover, a periphery of a wiring ( 15 ) for transmitting a signal is continuously covered by the conductor layer ( 12 ) and a conductor layer ( 19 ) with insulators ( 14 ), ( 16 ), ( 17 ) and ( 18 ) interposed therebeween in a section crossing a direction of extension thereof. The wiring ( 15 ) is electrically connected to the semiconductor substrate ( 1 ) through a conductive plug ( 13 ) filled in a contact hole ( 24 ) formed in the conductor layer ( 12 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a semiconductor device and amethod of manufacturing the semiconductor device, and more particularlyto an improvement for implementing an enhancement in a noise eliminatingcharacteristic of a wiring compatibly with promotion of microfabricationand simplification of a manufacturing process.

[0003] 2. Description of the Background Art

[0004]FIGS. 31 and 32 are sectional views showing a wiring structure fora high frequency used in a conventional semiconductor device which hasbeen described in the document (Y. Odate, T. Usami, K. Otsuka, T. Suga,“A measurement and simulation study of transmission lines on micro-stripand stacked-pair structure for high speed signals,” Proc. ElectronicComponents & technology Conference, pp. 526-529, May 2000.),illustrating a micro-strip line and a stacked pair line which areprovided over a semiconductor substrate, respectively. In themicro-strip line, a grounding conductor 203 is formed under atransmission line 201. Consequently, an electromagnetic field iscollected into the grounding conductor 203. For this reason, acharacteristic for eliminating the influence of a noise between thetransmission line 201 and another transmission line 202 (that is, anoise eliminating characteristic) can be enhanced.

[0005] However, there has been a problem in that the noise eliminatingcharacteristic is deteriorated if the transmission line 202 excessivelyapproaches the transmission line 201, and therefore instead, a stackedpair line structure has been proposed. In the stacked pair linestructure, the transmission line 201 and a grounding conductor 204 whichhave widths and thicknesses equal to each other are provided to make apair so that an electromagnetic field is caused to converge.Consequently, the noise eliminating characteristic can be enhanced.

[0006] Also in the stacked pair line, however, there has been a problemin that the noise eliminating characteristic cannot be sufficientlyobtained between the transmission line 201 and another transmission linearranged at the side thereof. In order to solve such a problem, acoaxial shield wiring structure has been proposed. FIG. 33 is asectional view showing a coaxial shield wiring structure disclosed inJapanese Patent Application Laid-Open No. 6-216343 (1994). In thecoaxial shield wiring structure, grounding conductors 211, 212, 213 and214 are provided through an insulating film 215 vertically andhorizontally with respect to a transmission line 210.

[0007] In the coaxial shield wiring structure, however, the groundingconductors 213 and 214 are provided on the left and right of thetransmission line 210. In addition, these wirings are formed throughtransfer using a mask pattern. Therefore, the degree of integration isthe same as that of an element formed according to a design rule whichis twice as much as a currently used design rule (a design rule means athreshold value of a lithography resolution). Thus, there has been aproblem in that microfabrication is inhibited. According to a wiringrule with microfabrication of 0.1 μm or less, furthermore, there hasbeen a problem in that the noise eliminating characteristic isdeteriorated between transmission lines arranged at the sides thereof Inaddition, it is necessary to form a special contact hole in order toelectrically connect the grounding conductors 211, 212, 213 and 214 to asemiconductor substrate. Therefore, there has been a problem in that aprocess for manufacturing a semiconductor device is complicated.

SUMMARY OF THE INVENTION

[0008] In order to solve the above-mentioned problems in theconventional art, it is an object of the present invention to provide ahigh-frequency semiconductor device capable of implementing anenhancement in a noise eliminating characteristic of a wiring compatiblywith promotion of microfabrication and simplification of a manufacturingprocess, and a method of manufacturing the semiconductor device.

[0009] A first aspect of the present invention is directed to ahigh-frequency semiconductor device comprising a semiconductor substratehaving a main surface, a first wiring provided over the main surface ofthe semiconductor substrate, and a conductor layer continuously coveringa periphery of the first wiring with a first insulator interposedtherebetween in a section crossing a direction of extension of the firstwiring.

[0010] A second aspect of the present invention is directed to thehigh-frequency semiconductor device according to the first aspect of thepresent invention, further comprising a second wiring provided over themain surface of the semiconductor substrate with an insulating filminterposed therebetween, the conductor layer continuously covering upperand side surfaces of the second wiring with a second insulatorinterposed therebetween in a section crossing a direction of extensionof the second wiring and being connected to the semiconductor substrate.

[0011] A third aspect of the present invention is directed to thehigh-frequency semiconductor device according to the first aspect of thepresent invention, wherein an upper surface of the conductor layer isflat.

[0012] A fourth aspect of the present invention is directed to thehigh-frequency semiconductor device according to the first aspect of thepresent invention, wherein the conductor layer transmits a sourcepotential.

[0013] A fifth aspect of the present invention is directed to thehigh-frequency semiconductor device according to the second aspect ofthe present invention, wherein the conductor layer continuously covers aperiphery of the second wiring in cooperation with the semiconductorsubstrate with the second insulator and the insulating film interposedtherebetween in the section crossing the direction of extension of thesecond wiring.

[0014] A sixth aspect of the present invention is directed to thehigh-frequency semiconductor device according to the first aspect of thepresent invention, wherein the first wiring is electrically connected tothe semiconductor substrate through a conductor plug filled in a throughhole selectively formed in the conductor layer with a side insulatingfilm interposed therebetween in a part taken in the direction ofextension of the first wiring.

[0015] A seventh aspect of the present invention is directed to thehigh-frequency semiconductor device according to the second aspect ofthe present invention, wherein a portion of the second insulator whichcovers the upper and side surfaces of the second wiring and is providedin contact with the conductor layer is formed of the same material.

[0016] An eighth aspect of the present invention is directed to thehigh-frequency semiconductor device according to the first aspect of thepresent invention, wherein a portion of the first insulator which coversupper and side surfaces of the first wiring and is provided in contactwith the conductor layer is formed of the same material.

[0017] A ninth aspect of the present invention is directed to a methodof manufacturing a high-frequency semiconductor device comprising thesteps of (A) preparing a semiconductor substrate having a main surface,(B) depositing a first conductor layer to cover the main surface of thesemiconductor substrate, (C) flattening an upper surface of the firstconductor layer, (D) forming a first insulating film on the uppersurface of the first conductor layer thus flattened, (E) depositing afirst conductive film on the first insulating film, (F) forming a secondinsulating film on the first conductive film, (G) patterning the firstconductive film and the second insulating film, thereby forming a firstwiring and a first upper insulating film covering an upper surfacethereof, (H) depositing a third insulating film to cover the uppersurface of the first conductor layer in such a thickness as to bury thefirst upper insulating film therein, (I) removing the third insulatingfilm to leave, as a first side wall, a portion covering side surfaces ofthe first wiring and the first upper insulating film, (J) removing thefirst insulating film to leave portions covered with the first wiringand the first side wall, simultaneously with the step (I) or after thestep (I), (K) depositing a second conductor layer to cover the uppersurface of the first conductor layer in such a thickness as to bury thefirst upper insulating film therein, and (L) flattening an upper surfaceof the second conductor layer to maintain such a configuration that thefirst upper insulating film is buried.

[0018] A tenth aspect of the present invention is directed to a methodof manufacturing a high-frequency semiconductor device comprising thesteps of (A) preparing a semiconductor substrate having a main surface,(B) depositing a first conductor layer to cover the main surface of thesemiconductor substrate, (C) flattening an upper surface of the firstconductor layer, (D) forming a first insulating film on the uppersurface of the first conductor layer thus flattened, (E) depositing afirst sacrificial layer on the first insulating film, (F) selectivelyforming, in the first sacrificial layer, a trench penetrating from anupper surface to a lower surface thereof, (G) depositing a conductivematerial to fill in the trench, (H) flattening the upper surface of thefirst sacrificial layer and an upper surface of the conductive material,thereby forming a first wiring of the conductive material, (I) forming asecond insulating film on the upper surface of the first sacrificiallayer and an upper surface of the first wiring, (J) removing the secondinsulating film to leave, as a first upper insulating film, a portionprovided on the first wiring, (K) removing the first sacrificial layer,(L) depositing a third insulating film to cover the upper surface of thefirst conductor layer in such a thickness as to bury the first upperinsulating film therein, (M) removing the third insulating film toleave, as a first side wall, a portion covering side surfaces of thefirst wiring and the first upper insulating film, (N) removing the firstinsulating film to leave portions covered with the first wiring and thefirst side wall, simultaneously with the step (M) or after the step (M),(O) depositing a second conductor layer to cover the upper surface ofthe first conductor layer in such a thickness as to bury the first upperinsulating film therein, and (P) flattening an upper surface of thesecond conductor layer to maintain such a configuration that the firstupper insulating film is buried.

[0019] An eleventh aspect of the present invention is directed to themethod of manufacturing a high-frequency semiconductor device accordingto the ninth aspect of the present invention, wherein the step (B)includes the steps of (B1) forming a fourth insulating film on the mainsurface, (B2) forming a second conductive film on the fourth insulatingfilm, (B3) forming a fifth insulating film on the second conductivefilm, (B4) patterning the second conductive film and the fifthinsulating film, thereby forming a second wiring and a second upperinsulating film covering an upper surface thereof, (B5) depositing asixth insulating film to cover the main surface of the semiconductorsubstrate in such a thickness as to bury the second upper insulatingfilm therein, (B6) removing the sixth insulating film to leave, as asecond side wall, a portion covering side surfaces of the second wiringand the second upper insulating film, (B7) removing the fourthinsulating film to leave portions covered with the second wiring and thesecond side wall, simultaneously with the step (B6) or after the step(B6), and (B8) depositing the first conductor layer to cover the mainsurface of the semiconductor substrate in such a thickness as to burythe second upper insulating film therein, and the step (C) includes thestep of (C1) flattening the upper surface of the first conductor layerto maintain such a configuration that the second upper insulating filmis buried.

[0020] A twelfth aspect of the present invention is directed to themethod of manufacturing a high-frequency semiconductor device accordingto the tenth aspect of the present invention, wherein the step (B)includes the steps of (B1) forming a fourth insulating film on the mainsurface, (B2) forming a second conductive film on the fourth insulatingfilm, (B3) forming a fifth insulating film on the second conductivefilm, (B4) patterning the second conductive film and the fifthinsulating film, thereby forming a second wiring and a second upperinsulating film covering an upper surface thereof, (B5) depositing asixth insulating film to cover the main surface of the semiconductorsubstrate in such a thickness as to bury the second upper insulatingfilm therein, (B6) removing the sixth insulating film to leave, as asecond side wall, a portion covering side surfaces of the second wiringand the second upper insulating film, (B7) removing the fourthinsulating film to leave portions covered with the second wiring and thesecond side wall, simultaneously with the step (B6) or after the step(B6), and (B8) depositing the first conductor layer to cover the mainsurface of the semiconductor substrate in such a thickness as to burythe second upper insulating film therein, and the step (C) includes thestep of (C1) flattening the upper surface of the first conductor layerto maintain such a configuration that the second upper insulating filmis buried.

[0021] A thirteenth aspect of the present invention is directed to themethod of manufacturing a high-frequency semiconductor device accordingto the ninth aspect of the present invention, further comprising thesteps of (AA) selectively forming, in the first insulating film and thefirst conductor layer, a through hole penetrating from an upper surfaceof the first insulating film to a lower surface of the first conductorlayer, after the step (D) and before the step (E), (BB) forming a sideinsulating film covering a side wall surface of the through hole beforethe step (E), and (CC) forming a conductive plug to fill in the throughhole with the side insulating film interposed therebetween before thestep (E), the first conductive film being also deposited on the throughhole to be connected to the conductive plug at the step (E), and thefirst wiring being formed to be connected to the conductive plug bycovering the through hole at the step (G).

[0022] A fourteenth aspect of the present invention is directed to themethod of manufacturing a high-frequency semiconductor device accordingto the twelfth aspect of the present invention, further comprising thesteps of (AA) depositing a second sacrificial layer to cover the mainsurface of the semiconductor substrate in such a thickness as to burythe second upper insulating film therein, after the step (B7) and beforethe step (B8), and (BB) patterning the second sacrificial layer to leavea part thereof as a columnar portion before the step (BB), the firstconductor layer being deposited to cover the main surface of thesemiconductor substrate in such a thickness as to bury the second upperinsulating film therein at the step (B8), and an upper surface of thecolumnar portion and the upper surface of the first conductor layerbeing flattened to maintain such a configuration that the second upperinsulating film is buried at the step (C1), and the method furthercomprising the steps of (CC) removing the columnar portion, therebyforming a through hole in the first conductor layer after the step (C1)and before the step (D), (DD) forming a side insulating film to cover aside wall surface of the through hole after the step (CC) and before thestep (D), and (EE) forming a conductive plug to fill in the through holewith the side insulating film interposed therebetween before the step(D), the step (D) including the steps of (D1) forming the firstinsulating film on the upper surface of the first conductor layer whichis flattened and over the through hole, and (D2) selectively removingthe first insulating film such that at least a part of an upper surfaceof the conductive plug is exposed, the first sacrificial layer beingdeposited on an exposed surface of the conductive plug as well as thefirst insulating film at the step (E), the trench being formed such thatthe exposed surface of the conductive plug is exposed at the step (F),and the conductive material being deposited to be connected to theexposed surface of the conductive plug at the step (G).

[0023] A fifteenth aspect of the present invention is directed to themethod of manufacturing a high-frequency semiconductor device accordingto the fourteenth aspect of the present invention, wherein at least anupper surface portion of the fifth insulating film and the sixthinsulating film are formed of the same material and the secondsacrificial layer is formed of another material different therefrom.

[0024] A sixteenth aspect of the present invention is directed to themethod of manufacturing a high-frequency semiconductor device accordingto the tenth aspect of the present invention, wherein at least an uppersurface portion of the second insulating film and the third insulatingfilm are formed of the same material.

[0025] According to the first aspect of the present invention, theperiphery of the first wiring is continuously covered by the conductorlayer with the insulator interposed therebetween in the section crossingthe direction of extension thereof. By using the conductor layer as apower line (including a grounding conductor), therefore, it is possibleto more reduce a noise entering the first wiring and a noise emittedfrom the first wiring than that in a conventional device. Moreover, theconductor layer can be formed to bury the first wiring therein.Accordingly, microfabrication of an element is not prevented.Furthermore, it is not necessary to form a contact hole in order toimplement electrical connection of the conductor layer to thesemiconductor substrate. Consequently, a manufacturing process can besimplified. Thus, it is possible to achieve an enhancement in a noiseeliminating characteristic of the wiring compatibly with promotion ofthe microfabrication and the simplification of the manufacturingprocess.

[0026] According to the second aspect of the present invention, theupper and side surfaces of the second wiring are continuously covered bythe conductor layer with the insulator interposed therebetween in thesection crossing the direction of extension thereof, and the conductorlayer is connected to the semiconductor substrate. By using theconductor layer as a power line (including a grounding conductor),therefore, it is possible to more reduce a noise entering the secondwiring, a noise emitted from the second wiring and a noise influencingbetween the first wiring and the second wiring than that in aconventional device.

[0027] According to the third aspect of the present invention, the uppersurface of the conductor layer is flat. Therefore, it is easy to furtherprovide an upper wiring over the conductor layer by using the presentdevice as an intermediate product in a semiconductor process.

[0028] According to the fourth aspect of the present invention, theconductor layer is formed as a power line (including a groundingconductor). Therefore, it is possible to more reduce a noise enteringthe first and second wirings, a noise emitted from the first and secondwirings and a noise influencing the first wiring and the second wiringthan that in a conventional device.

[0029] According to the fifth aspect of the present invention, theconductor layer continuously covers the periphery of the second wiringin cooperation with the semiconductor substrate with the secondinsulator and the insulating film interposed therebetween in the sectioncrossing the direction of extension of the second wiring. Therefore, thenoise eliminating characteristic for the second wiring can further beenhanced.

[0030] According to the sixth aspect of the present invention, thethrough hole and the conductive plug are provided in the conductorlayer. Therefore, the first wiring positioned on an upper layer can beconnected to the semiconductor substrate without a difficulty in amanufacturing process in the same manner as in a conventional well knownsemiconductor device.

[0031] According to the seventh aspect of the present invention, theportion of the second insulator which covers the upper and side surfacesof the second wiring and is provided in contact with the conductor layeris formed of the same material. Therefore, in the case in which theconductor layer is to be formed by using a damascene process, a contacthole for connecting the upper wiring to the semiconductor substrate caneasily be formed in the conductor layer.

[0032] According to the eighth aspect of the present invention, theportion of the first insulator which covers the upper and side surfacesof the first wiring and is provided in contact with the conductor layeris formed of the same material. Therefore, in the case in which theconductor layer is to be formed by using the damascene process, acontact hole for connecting the first wiring to the upper wiring caneasily be formed in the conductor layer.

[0033] According to the ninth aspect of the present invention, thesemiconductor device according to the first aspect of the presentinvention can easily be manufactured by a combination of a conventionalwell-known semiconductor process, for example, film formation,patterning and the like.

[0034] According to the tenth aspect of the present invention, thesemiconductor device according to the first aspect of the presentinvention can easily be manufactured by a combination of a conventionalwell-known semiconductor process, for example, film formation,patterning and the like, particularly, by employing the damasceneprocess. Accordingly, the method is suitable for using a metalcontaining copper as a main component for a material of the conductorlayer.

[0035] According to the eleventh aspect of the present invention, thesemiconductor device according to the second aspect of the presentinvention can easily be manufactured by a combination of a conventionalwell-known semiconductor process, for example, film formation,patterning and the like.

[0036] According to the twelfth aspect of the present invention, thesemiconductor device according to the second aspect of the presentinvention can easily be manufactured by a combination of a conventionalwell-known semiconductor process, for example, film formation,patterning and the like, particularly, by employing the damasceneprocess.

[0037] According to the thirteenth aspect of the present invention, thesemiconductor device according to the sixth aspect of the presentinvention can easily be manufactured by a combination of a conventionalwell-known semiconductor process, for example, film formation,patterning and the like.

[0038] According to the fourteenth aspect of the present invention, thesemiconductor device according to the sixth aspect of the presentinvention can easily be manufactured by a combination of a conventionalwell-known semiconductor process, for example, film formation,patterning and the like, particularly, by employing the damasceneprocess.

[0039] According to the fifteenth aspect of the present invention, atleast the upper surface portion of the fifth insulating film and thesixth insulating film are formed of the same material and the secondsacrificial layer is formed of another material different therefrom.Therefore, in the case in which the first conductor layer is to beformed by using the damascene process, a contact hole for connecting theupper wiring to the semiconductor substrate can easily be formed in thefirst conductor layer.

[0040] According to the sixteenth aspect of the present invention, atleast the upper surface portion of the second insulating film and thethird insulating film are formed of the same material. Therefore, in thecase in which the first conductor layer is to be formed by using thedamascene process, a contact hole for connecting the first wiring to theupper wiring can easily be formed in the second conductor layer.

[0041] These and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042]FIG. 1 is a front sectional view showing a semiconductor deviceaccording to a first embodiment,

[0043] FIGS. 2 to 13 are views showing a process for manufacturing thedevice illustrated in FIG. 1,

[0044]FIG. 14 is a front sectional view showing a semiconductor deviceaccording to a second embodiment,

[0045] FIGS. 15 to 26 are views showing a process for manufacturing thedevice illustrated in FIG. 14,

[0046]FIG. 27 is a view showing a process for manufacturing asemiconductor device according to a variant of the second embodiment,

[0047] FIGS. 28 to 30 are views showing a process for manufacturing thedevice illustrated in FIG. 27, and

[0048] FIGS. 31 to 33 are front sectional views showing a wiringstructure to be used in a conventional semiconductor device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] First Embodiment

[0050] (Structure of Device)

[0051]FIG. 1 is a front sectional view showing a semiconductor deviceaccording to a first embodiment of the present invention. Thissemiconductor device 101 has a semiconductor substrate 1 and a wiringstructure formed thereover. The semiconductor substrate 1 is a siliconsubstrate having a main surface in which an insulating film 3 to be atrench isolation structure (STI: Shallow Trench Isolation) and animpurity introduced layer 2 are selectively formed. In the wiringstructure, a plurality of wirings 6 to be lower wirings for signaltransmission and a plurality of wirings 15 to be upper wirings forsignal transmission are formed over the semiconductor substrate 1. Bothof the wirings 6 and 15 are constituted to transmit a high-frequencyelectric signal of 1 GHz or more.

[0052] The wiring 6 is opposed to the main surface of the semiconductorsubstrate 1 with an insulating film 5 interposed therebetween. Upperinsulating films 7 and 9 are formed on the wiring 6. Moreover, a sidewall 8 to be an insulator is formed on side surfaces of the wiring 6 andthe upper insulating films 7 and 9. In other words, the wiring 6 issurrounded by the insulator in a section perpendicular to a direction ofextension thereof. The wiring 6 and the insulator covering a peripherythereof are buried in a conductor layer 12 formed to cover thesemiconductor substrate 1. In a section perpendicular to the directionof extension of the wiring 6, accordingly, upper and side surfaces ofthe wiring 6 are continuously covered by the conductor layer 12 with theinsulator interposed therebetween. A material of the conductor layer 12is a metal containing aluminum as a main component (including thealuminum itself).

[0053] The conductor layer 12 has an upper surface flattened and a lowersurface partially connected electrically to the impurity introducedlayer 2 formed in the main surface of the semiconductor substrate 1. Asilicide film (semiconductor metal compound film) 4 is formed on aportion in the main surface of the semiconductor substrate 1 which is tobe electrically connected to the conductor layer 12. Moreover, aninsulating film 10 is formed in a portion where the conductor layer 12and the semiconductor substrate 1 are to be electrically insulated fromeach other.

[0054] The wiring 15 is provided opposite to the upper surface of theconductor layer 12 with an insulating film 14 interposed therebetween.Upper insulating films 16 and 18 are formed on the wiring 15. Moreover,a side wall 17 to be an insulator is formed on side surfaces of thewiring 15 and the upper insulating films 16 and 18. In other words, thewiring 15 is surrounded by the insulator in a section perpendicular to adirection of extension thereof. A conductor layer 19 is formed to burythe wiring 15 and the insulator covering a periphery of the wiring 15therein and to cover the upper surface of the conductor layer 12. Amaterial of the conductor layer 19 is a metal containing aluminum as amain component similarly to the conductor layer 12.

[0055] The conductor layer 19 has an upper surface flattened and a lowersurface connected integrally with the upper surface of the conductorlayer 12. In a section perpendicular to the direction of extension ofthe wiring 15, accordingly, the periphery of the wiring 15 iscontinuously covered by the conductor layers 12 and 19 with an insulatorinterposed therebetween. The conductor layers 12 and 19 are connected toone of power lines of the semiconductor device 101. More specifically, apair of power input terminals (not shown) are formed in thesemiconductor device 101 and the conductor layers 12 and 19 areconnected to one of the power input terminals. Preferably, the conductorlayers 12 and 19 are grounding conductors for transmitting a groundingpotential.

[0056] The conductor layer 12 is provided with a contact hole 24 under apart in the direction of extension of the conductor 15. The inside ofthe contact hole 24 is provided with a side insulating film 11 coveringa side wall surface thereof and a conductive plug 13 filled in thecontact hole 24 with the side insulating film 11 interposedtherebetween. The conductive plug 13 is connected to a lower surface ofthe conductor 15, and furthermore, is electrically connected through asilicide film 4 to the impurity introduced layer 2 provided in the mainsurface of the semiconductor substrate 1. In other words, the conductor15 is electrically connected to the semiconductor substrate 1 throughthe conductive plug 13.

[0057] Referring to each element, an example of a material and adimension will be listed below. All values of the dimension are roughestimations. The semiconductor substrate 1 is a P-type siliconsubstrate. The impurity introduced layer 2 is an N⁺ diffusion layer. Theinsulating film 3 is a TEOS (tetraethyl orthosilicate) film or an HTO(high temperature oxide; high temperature thermal CVD oxide) film whichhas a thickness of 300 nm. A material of the silicide film 4 is CoSi orTiSi. The insulating film 5 is a thermal oxide film (SiO₂) or a thermalnitride oxide film (SiON) which has a thickness of 3 nm. The wiring 6 isa polysilicon film having a width of 100 nm and a thickness of 200 nm.The upper insulating film 7 is a TEOS film having a thickness of 100 nm.

[0058] The side wall 8 is a nitride film (Si₃N₄) having a thickness of50 nm and the upper insulating film 9 is a nitride film (Si₃N₄) having athickness of 100 nm. The insulating film 10 and the side insulating film11 are TEOS films. The conductor layer 12 has a thickness of 500 nm. Amaterial of the conductive plug 13 is polysilicon. The insulating film14 is a TEOS film having a thickness of 100 nm. The wiring 15 is a metalfilm containing, as a main component, aluminum having a width of 100 nmand a thickness of 200 nm. The upper insulating film 16 is a TEOS filmhaving a thickness of 100 nm. The side wall 17 is a nitride film (Si₃N₄)having a thickness of 50 nm. The upper insulating film 18 is a nitridefilm (Si₃N₄) having a thickness of 100 nm. The conductor layer 19 has athickness of 500 nm.

[0059] (Manufacturing Method)

[0060] FIGS. 2 to 13 are views showing a manufacturing process,illustrating a preferred method of manufacturing the semiconductordevice 101. In the following description, all numeric values related tomanufacturing conditions are rough estimations. In order to manufacturethe semiconductor device 101, first of all, a step shown in FIG. 2 isexecuted. At the step shown in FIG. 2, the semiconductor substrate 1being a P-type silicon substrate is first prepared. By using selectiveetching, next, a trench having a depth of 300 nm is selectively formedin the main surface of the semiconductor substrate 1 in accordance witha pattern of an isolation region (an isolation pattern). Subsequently,an oxide film such as a TEOS film or an HTO film is buried as theinsulating film 3 in the trench. Consequently, the isolation regionhaving a trench isolation structure (STI) is formed. Then, wellimplantation, isolation implantation and channel implantation arecarried out on the main surface of the semiconductor substrate 1, andfurthermore, a heat treatment for activation of an implanted impurity orthe like is performed (not shown). Since the well implantation, theisolation implantation and the channel implantation are carried out in aconventional well-known process, detailed description thereof will beomitted.

[0061] At a step shown in FIG. 3, next, oxidation is carried out so thatan oxide film (SiO₂) having a thickness of 3 nm is formed as theinsulating film 5 on the main surface of the semiconductor substrate 1.

[0062] At a step shown in FIG. 4, subsequently, a polysilicon filmhaving a thickness of 200 nm, a TEOS film having a thickness of 100 nmand a nitride film (Si₃N₄) having a thickness of 100 nm are firstdeposited sequentially on the insulating film 5. Then, the selectiveetching using a gate mask is carried out. Consequently, a three-layeredstructure including the wiring 6 and the upper insulating films 7 and 9is formed.

[0063] At a step shown in FIG. 5, a nitride film (Si₃N₄) is firstdeposited to cover the semiconductor substrate 1. The nitride film isdeposited such that the three-layered structure is buried therein. Then,the nitride film thus deposited is etched back so that the side wall 8covering a side surface of the three-layered structure is formed. Duringthis process, a portion of the insulating film 5 which is not coveredwith the three layered structure and the side wall 8 is also removedsimultaneously.

[0064] At a step shown in FIG. 6, an N-type impurity ion is firstimplanted by using the three-layered structure including the side wall 8as a shield. Consequently, the impurity introduced layer 2 is formed inthe exposed main surface of the semiconductor substrate 1. Theintroduced N-type impurity is activated through a subsequent heattreatment. The heat treatment is carried out at a temperature of 850° C.for 30 minutes by using a furnace or at a temperature of 1000° C. for 30seconds by using an RAT (ramp annealing device).

[0065] At a step shown in FIG. 7, subsequently, cobalt (Co) is depositedon the exposed main surface of the semiconductor substrate 1 and a heattreatment is carried out at a temperature of 600° C. by using the RAT.As a result, CoSi is formed as the silicide film 4 on a surface of theimpurity introduced layer 2.

[0066] At a step shown in FIG. 8, a TEOS film is deposited to cover themain surface of the semiconductor substrate 1 and is then etchedselectively by using a mask. Consequently, a portion in the main surfaceof the semiconductor substrate 1 to which the conductor layer 12 to beformed at a subsequent step is not connected is covered with theinsulating film 10.

[0067] At a step shown in FIG. 9, first of all, aluminum is deposited tocover the main surface of the semiconductor substrate 1. Then, an uppersurface of an aluminum layer is flattened by using CMP (chemicalmechanical polishing). Consequently, the conductor layer 12 having athickness of 500 nm is formed. The CMP is carried out such that theupper insulating film 9 is not exposed from the conductor layer 12.

[0068] At a step shown in FIG. 10, first of all, a TEOS film having athickness of 100 nm is deposited as the insulating film 14 on an uppersurface of the conductor layer 12. Then, selective etching using acontact mask is executed. Consequently, the contact hole 24 reaching thesilicide film 4 from an upper surface of the insulating film 14 throughthe conductor layer 12 and the insulating film 10 is selectively formedin the insulating film 14, the conductor layer 12 and the insulatingfilm 10. The contact hole 24 is formed just over a part of the impurityintroduced layer 2.

[0069] At a step shown in FIG. 11, first of all, a TEOS film having athickness of 20 nm is deposited on the inside of the contact hole 24 andthe insulating film 14. Then, etch back is carried out so that the sideinsulating film 11 covering a side wall surface of the contact hole 24is formed. Subsequently, polysilicon is deposited to fill in the insideof the side insulating film 11 and to cover the insulating film 14.Then, the CMP is executed until the insulating film 14 is exposed sothat the polysilicon provided on the insulating film 14 is removed andan upper surface of the polysilicon filled in the contact hole 24 withthe side insulating film 11 interposed therebetween is flattenedtogether with an upper surface of the insulating film 14. Thepolysilicon filled in the contact hole 24 acts as the conductive plug13.

[0070] At a step shown in FIG. 12, first of all, an aluminum film havinga thickness of 200 nm, a TEOS film having a thickness of 50 nm and anitride film (Si₃N₄) having a thickness of 100 nm are sequentiallydeposited on the insulating film 14 and the conductive plug 13. Then,the selective etching using a mask is carried out. Consequently, athree-layered structure including the wiring 15 and the upper insulatingfilms 16 and 18 is formed.

[0071] At a step shown in FIG. 13, a nitride film (Si₃N₄) is firstdeposited to cover the upper surface of the conductor layer 12. Thenitride film is deposited such that the three-layered structure isburied therein. Then, the nitride film thus deposited is etched back sothat the side wall 17 covering a side surface of the three-layeredstructure is formed. During this process, a portion of the insulatingfilm 14 which is not covered with the three-layered structure and theside wall 17 is also removed simultaneously. As a result, the uppersurface of the conductor layer 12 is selectively exposed.

[0072] Returning to FIG. 1, subsequently, aluminum is first deposited tocover the upper surface of the conductor layer 12. Then, an uppersurface of an aluminum layer is flattened by using the CMP (chemicalmechanical polishing). Consequently, the conductor layer 19 having athickness of 500 nm is formed. The CMP is carried out such that theupper insulating film 18 is not exposed from the conductor layer 19.Through the above-mentioned steps, the semiconductor device 101 shown inFIG. 1 is completed.

[0073] The material and dimension of each element described above areillustrative and it is a matter of course that other materials anddimensions can also be used. For example, generally, a semiconductorsubstrate other than the silicon substrate can also be used for thesemiconductor substrate 1.

[0074] (Advantage of First Embodiment)

[0075] As described above, in the semiconductor device 101, theperiphery of the wiring 15 to be a signal transmission wiring iscontinuously covered by the conductor layers 12 and 19 with theinsulator interposed therebetween in the section crossing the directionof extension thereof. Consequently, a noise eliminating characteristicbetween the wiring 15 and another wiring (for example, the wiring 15adjacently provided at the side thereof or the wiring 6 adjacentlyprovided thereunder) can be more enhanced than that in any of the wiringstructures shown in FIGS. 31 to 33.

[0076] Moreover, the upper and side surfaces of the wiring 6 to be thesignal transmission wiring are continuously covered by the conductorlayer 12 with the insulator interposed therebetween in the sectioncrossing the direction of extension thereof, and the conductor layer 12is connected to the semiconductor substrate 1. Consequently, the noiseeliminating characteristic between the wiring 6 and another wiring (forexample, the wiring 6 adjacently provided at the side thereof or thewiring 15 adjacently provided thereabove) can be more enhanced than thatin any of the wiring structures shown in FIGS. 31 to 33.

[0077] Furthermore, the conductor layers 12 and 19 are formed such thatthe wirings 6 and 15 are buried therein, and the same patterning as thatof each of the wirings 6 and 15 is not required. Differently from thecoaxial shield wiring structure shown in FIG. 33 which requires thepatterning, therefore, microfabrication of the element fabricated in thesemiconductor device 101 is not inhibited. Furthermore, it is notnecessary to form a contact hole in order to implement electricalconnection of the conductor layers 12 and 19 and the semiconductorsubstrate 1. Consequently, the manufacturing process can be simplified.Thus, the semiconductor device 101 and the method of manufacturing thesemiconductor device 101 can implement an enhancement in the noiseeliminating characteristic of the wiring compatibly with promotion ofthe microfabrication and simplification of the manufacturing process.

[0078] According to the method of manufacturing the semiconductor device101 described above, moreover, the upper surface of the conductor layer12 is formed flatly. Therefore, the upper wiring 15 can easily be formedon the conductor layer 12. Furthermore, the upper surface of theconductor layer 19 is flat. Therefore, it is easy to provide a wiring tobe a third layer (not shown) over the conductor layer 19. Also in thefinished semiconductor device 101, furthermore, the wirings 6 and 15 arenot only surrounded by the conductor layers 12 and 19 but also buried inthe conductor layers 12 and 19 having the upper surfaces flattened.Consequently, the noise eliminating characteristics of the wirings 6 and15 can further be enhanced.

[0079] (Second Embodiment)

[0080] (Structure of Device)

[0081]FIG. 14 is a front sectional view showing a semiconductor deviceaccording to a second embodiment of the present invention. Thissemiconductor device 102 is characteristically different from thesemiconductor device 101 (FIG. 1) according to the first embodiment inthat conductor layers 62 and 69 covering a plurality of wirings 6 actingas lower wirings and a plurality of wirings 65 acting as upper wiringsare formed of a metal containing copper as a main component (includingthe copper itself). The wiring 65 is constituted to transmit ahigh-frequency electric signal of 1 GHz or more similarly to the wiring15 of the semiconductor device 101.

[0082] The wiring 65 is provided opposite to a flat upper surface of theconductor layer 62 with an insulating film 64 interposed therebetween.An upper insulating film 66 is formed on the wiring 65. Moreover, a sidewall 67 to be an insulator is formed on side surfaces of the wiring 65and the upper insulating film 66. In other words, the wiring 65 issurrounded by the insulator in a section perpendicular to a direction ofextension thereof. The conductor layer 69 is formed to bury the wiring65 and the insulator coving a periphery of the wiring 65 therein and tocover an upper surface of the conductor layer 62.

[0083] The conductor layer 69 has an upper surface flattened and a lowersurface connected integrally with the upper surface of the conductorlayer 62. In a section perpendicular to the direction of extension ofthe wiring 65, accordingly, a periphery of the wiring 65 is continuouslycovered by the conductor layers 62 and 69 with an insulator interposedtherebetween. The conductor layers 62 and 69 are connected to one ofpower lines of the semiconductor device 102. More specifically, a pairof power input terminals (not shown) are formed in the semiconductordevice 102 in the same manner as in the semiconductor device 101, andthe conductor layers 62 and 69 are connected to one of the power inputterminals, preferably, the terminal to which a grounding potential is tobe applied.

[0084] The conductor layer 62 is provided with a contact hole 74 under apart in the direction of extension of the conductor 65. The inside ofthe contact hole 74 is provided with a side insulating film 61 coveringa side wall surface thereof and a conductive plug 63 filled in thecontact hole 74 with the side insulating film 61 interposedtherebetween. The conductive plug 63 is connected to a lower surface ofthe conductor 65, and furthermore, is electrically connected through asilicide film 4 to an impurity introduced layer 2 provided in a mainsurface of a semiconductor substrate 1. In other words, the conductor 65is electrically connected to the semiconductor substrate 1 through theconductive plug 63.

[0085] Referring to each element which is not provided in thesemiconductor device 101 (FIG. 1), an example of a material anddimension will be listed below. All values of the dimension are roughestimations. An insulating film 60 and the side insulating film 61substituted for the insulating film 10 and the side wall insulating film11 in the semiconductor device 101 (FIG. 1) are nitride films (Si₃N₄).The conductor layer 62 has a thickness of 500 nm. A material of theconductive plug 63 is a metal containing copper as a main component. Theinsulating film 64 is a nitride film (Si₃N₄). The wiring 65 is a metalfilm containing, as a main component, copper having a width of 100 nmand a thickness of 200 nm. The upper insulating film 66 is a TEOS filmhaving a thickness of 200 nm. The side wall 67 is a nitride film (Si₃N₄)having a thickness of 50 nm. The conductor layer 69 has a thickness of500 nm.

[0086] (Manufacturing Method)

[0087] FIGS. 15 to 27 are views showing a manufacturing process,illustrating a preferred method of manufacturing the semiconductordevice 102. In the following description, all numeric values related tomanufacturing conditions are rough estimations. In order to manufacturethe semiconductor device 102, the steps shown in FIGS. 2 to 7 are firstexecuted and the step shown in FIG. 15 is then executed. At the stepshown in FIG. 15, a nitride film (Si₃N₄) is deposited to cover the mainsurface of the semiconductor substrate 1, and is then etched selectivelyby using a mask. Consequently, a portion in the main surface of thesemiconductor substrate 1 to which the conductor layer 62 to be formedat a subsequent step is not connected is covered with the insulatingfilm 60.

[0088] At a step shown in FIG. 16, subsequently, a TEOS layer is firstdeposited to cover the main surface of the semiconductor substrate 1.Then, an upper surface of the TEOS layer is flattened by using CMP sothat a TEOS layer 72 having a thickness of 500 nm is formed as asacrificial layer (a layer to be formed for utilization as a mold and tobe removed at a subsequent step will be provisionally referred to as asacrificial layer in this specification). The CMP is carried out suchthat an upper insulating film 9 is not exposed from the TEOS layer 72.

[0089] At a step shown in FIG. 17, then, selective etching using apositive mask of a contact hole is carried out so that the TEOS layer 72is subjected to patterning. As a result, the TEOS layer 72 is removedleaving a columnar portion just over a part of the impurity introducedlayer 2.

[0090] At a step shown in FIG. 18, subsequently, copper is firstdeposited to cover the main surface of the semiconductor substrate 1 andto bury the upper insulating film 9 therein. Then, an upper surface of acopper layer and an upper surface of the columnar TEOS layer 72 areflattened by using the CMP. Consequently, the conductor layer 62 havinga thickness of 500 nm is formed. The CMP is carried out such that theupper insulating film 9 is not exposed from the conductor layer 62.

[0091] At a step shown in FIG. 19, subsequently, the TEOS layer 72 andthe insulating film 60 provided thereunder are first removed so that thecontact hole 74 is formed in the conductor layer 62. The contact hole 74is formed just over a part of the impurity introduced layer 2 so thatthe silicide film 4 is exposed. Then, a nitride film (Si₃N₄) isdeposited on the inside of the contact hole 74 and the conductor layer62. Thereafter, etch back is carried out so that the side insulatingfilm 61 covering a side wall surface of the contact hole 74 is formed.

[0092] At a step shown in FIG. 20, subsequently, copper is deposited tofill in the inside of the side insulating film 61 and to cover the uppersurface of the conductor layer 62. Then, the CMP is executed until theupper surface of the conductor layer 62 and an upper edge of the sideinsulating film 61 are exposed. Consequently, the upper surface of theconductor layer 62, the upper edge of the side insulating film 61 and anupper surface of a copper layer filled in the contact hole 74 with theside insulating film 61 interposed therebetween are flattened. Thecopper layer filled in the contact hole 74 acts as the conductive plug63.

[0093] At a step shown in FIG. 21, first of all, the nitride film 64 isdeposited on the upper surface of the conductor layer 62, the upper edgeof the side insulating film 61 and an upper surface of the conductiveplug 63. Then, selective etching is executed by using a contact mask.Consequently, a portion of the nitride film which is provided just overthe contact hole 74 is selectively removed. Subsequently, a nitride filmis deposited again, and furthermore, is etched back. Thus, an annularside wall portion of the nitride film is opened on the upper surface ofthe conductive plug 63. The conductive plug 63 is exposed in a portionsurrounded by the annular side wall portion.

[0094] At a step shown in FIG. 22, then, the conductor layer 65 isformed by using a so-called damascene process. In other words, the TEOSlayer 71. to be a sacrificial layer is first deposited on the insulatingfilm 64 and the conductive plug 63. Thereafter, selective etching usinga mask is carried out so that a trench 75 is formed in a portion of theTEOS layer 71 where the wiring 65 is to be formed. The trench 75 isformed such that the exposed portion of the conductive plug 63 isexposed. Subsequently, copper is deposited to fill in the trench 75 andan upper surface of the deposited copper and an upper surface of theTEOS layer 71 are then flattened by using the CMP. Consequently, thewiring 65 is formed in the trench 75. The wiring 65 is connectedintegrally with the conductive plug 63.

[0095] At a step shown in FIG. 23, subsequently, a TEOS film and anitride film (Si₃N₄) are first deposited sequentially on the TEOS layer71 and the wiring 65. Then, selective etching is carried out by using amask. Consequently, the upper insulating film 66 and the nitride film 76are formed on the wiring 65. During this process, the TEOS layer 71 isremoved simultaneously.

[0096] At a step shown in FIG. 24, then, a nitride film (Si₃N₄) isdeposited to cover the upper surface of the conductor layer 62. Thenitride film is deposited in such a thickness that the nitride film 76is buried therein. Thereafter, the nitride film thus deposited is etchedback. During this process, the nitride film 76 is removedsimultaneously. Consequently, the side wall 67 is formed to cover theside surfaces of the wiring 65 and the upper insulating film 66. Aportion of the insulating film 64 which is not covered with the wiring65 and the side wall 67 is also removed simultaneously. As a result, theupper surface of the conductor layer 62 is selectively exposed.

[0097] At a step shown in FIG. 25, subsequently, copper is firstdeposited to cover the upper surface of the conductor layer 62. Then, anupper surface of a copper layer is flattened by using the CMP so thatthe conductor layer 69 having a thickness of 500 nm is formed. The CMPis carried out such that the upper insulating film 66 is not exposedfrom the conductor layer 69.

[0098] As shown in FIG. 26, preferably, the insulating film 70 being anitride film (Si₃N₄) is then deposited on the conductor layer 69.Through the above-mentioned steps, the semiconductor device 102 shown inFIG. 14 is completed.

[0099] (Advantage of Second Embodiment)

[0100] Also in the semiconductor device 102 and the method ofmanufacturing the semiconductor device 102, the same effects as those inthe semiconductor device 101 and the method of manufacturing thesemiconductor device 101 can be obtained. Furthermore, a metalcontaining, as a main component, copper having a low electricalresistivity is used for the materials of the conductor layers 62 and 69.In comparison with the same dimension, therefore, the noise eliminatingcharacteristic can further be enhanced.

[0101] In particular, the method of manufacturing the semiconductordevice 102 described above employs the so-called damascene process sothat a metal containing copper as a main component can be used for thematerials of the conductor layers 62 and 69. Particularly, the side wall8 exposed to a surface and the upper insulating film 9 in the insulatorsurrounding the wiring 6 are formed of the same material (a nitride).Therefore, the TEOS layer 72 formed of another material is used for asacrificial layer and can be subjected to the patterning withoutdamaging the insulator surrounding the wiring 6 at the step shown inFIG. 17. In other words, the contact hole 74 can be formed.

[0102] In order to further provide a wiring to be a third layer on theconductor layer 69 and to form, on the conductor layer 69, a contacthole for electrically connecting the wiring to be the third layer andthe wiring 65 to be a second layer, it is preferable that the surface ofthe insulator surrounding the wiring 65 should be formed of the samematerial. FIGS. 27 to 30 are views showing a manufacturing process,illustrating a manufacturing method suitable for the purpose. The stepsshown in FIGS. 27 to 30 are executed in place of the steps shown inFIGS. 23 to 26. In FIG. 27, a nitride film 76 is formed on a TEOS layer71 more thickly than that in the step shown in FIG. 23. As a result,when a nitride film is deposited and is further etched back at the stepshown in FIG. 28, a part of the nitride film 76 is not removed butremains as an upper insulating film 75 on the TEOS layer 71.Accordingly, the upper insulating film 75 also remains exactly on thefinished semiconductor device 102 which is obtained by forming aconductor layer 69 at the step shown in FIG. 29 and further forming aninsulating film 70 at the step shown in FIG. 30.

[0103] While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

What is claimed is:
 1. A high-frequency semiconductor device comprising:a semiconductor substrate having a main surface; a first wiring providedover said main surface of said semiconductor substrate; and a conductorlayer continuously covering a periphery of said first wiring with afirst insulator interposed therebetween in a section crossing adirection of extension of said first wiring.
 2. The high-frequencysemiconductor device according to claim 1, further comprising a secondwiring provided over said main surface of said semiconductor substratewith an insulating film interposed therebetween, said conductor layercontinuously covering upper and side surfaces of said second wiring witha second insulator interposed therebetween in a section crossing adirection of extension of said second wiring and being connected to saidsemiconductor substrate.
 3. The high-frequency semiconductor deviceaccording to claim 1, wherein an upper surface of said conductor layeris flat.
 4. The high-frequency semiconductor device according to claim1, wherein said conductor layer transmits a source potential.
 5. Thehigh-frequency semiconductor device according to claim 2, wherein saidconductor layer continuously covers a periphery of said second wiring incooperation with said semiconductor substrate with said second insulatorand said insulating film interposed therebetween in said sectioncrossing said direction of extension of said second wiring.
 6. Thehigh-frequency semiconductor device according to claim 1, wherein saidfirst wiring is electrically connected to said semiconductor substratethrough a conductor plug filled in a through hole selectively formed insaid conductor layer with a side insulating film interposed therebetweenin a part taken in said direction of extension of said first wiring. 7.The high-frequency semiconductor device according to claim 2, wherein aportion of said second insulator which covers said upper and sidesurfaces of said second wiring and is provided in contact with saidconductor layer is formed of the same material.
 8. The high-frequencysemiconductor device according to claim 1, wherein a portion of saidfirst insulator which covers upper and side surfaces of said firstwiring and is provided in contact with said conductor layer is formed ofthe same material.
 9. A method of manufacturing a high-frequencysemiconductor device comprising the steps of: (A) preparing asemiconductor substrate having a main surface; (B) depositing a firstconductor layer to cover said main surface of said semiconductorsubstrate; (C) flattening an upper surface of said first conductorlayer; (D) forming a first insulating film on said upper surface of saidfirst conductor layer thus flattened; (E) depositing a first conductivefilm on said first insulating film; (F) forming a second insulating filmon said first conductive film; (G) patterning said first conductive filmand said second insulating film, thereby forming a first wiring and afirst upper insulating film covering an upper surface thereof; (H)depositing a third insulating film to cover said upper surface of saidfirst conductor layer in such a thickness as to bury said first upperinsulating film therein; (I) removing said third insulating film toleave, as a first side wall, a portion covering side surfaces of saidfirst wiring and said first upper insulating film; (J) removing saidfirst insulating film to leave portions covered with said first wiringand said first side wall, simultaneously with said step (I) or aftersaid step (I); (K) depositing a second conductor layer to cover saidupper surface of said first conductor layer in such a thickness as tobury said first upper insulating film therein; and (L) flattening anupper surface of said second conductor layer to maintain such aconfiguration that said first upper insulating film is buried.
 10. Amethod of manufacturing a high-frequency semiconductor device comprisingthe steps of: (A) preparing a semiconductor substrate having a mainsurface; (B) depositing a first conductor layer to cover said mainsurface of said semiconductor substrate; (C) flattening an upper surfaceof said first conductor layer; (D) forming a first insulating film onsaid upper surface of said first conductor layer thus flattened; (E)depositing a first sacrificial layer on said first insulating film; (F)selectively forming, in said first sacrificial layer, a trenchpenetrating from an upper surface to a lower surface thereof; (G)depositing a conductive material to fill in said trench; (H) flatteningsaid upper surface of said first sacrificial layer and an upper surfaceof said conductive material, thereby forming a first wiring of saidconductive material; (I) forming a second insulating film on said uppersurface of said first sacrificial layer and an upper surface of saidfirst wiring; (J) removing said second insulating film to leave, as afirst upper insulating film, a portion provided on said first wiring;(K) removing said first sacrificial layer; (L) depositing a thirdinsulating film to cover said upper surface of said first conductorlayer in such a thickness as to bury said first upper insulating filmtherein; (M) removing said third insulating film to leave, as a firstside wall, a portion covering side surfaces of said first wiring andsaid first upper insulating film; (N) removing said first insulatingfilm to leave portions covered with said first wiring and said firstside wall, simultaneously with said step (M) or after said step (M); (O)depositing a second conductor layer to cover said upper surface of saidfirst conductor layer in such a thickness as to bury said first upperinsulating film therein; and (P) flattening an upper surface of saidsecond conductor layer to maintain such a configuration that said firstupper insulating film is buried.
 11. The method of manufacturing ahigh-frequency semiconductor device according to claim 9, wherein saidstep (B) includes the steps of: (B1) forming a fourth insulating film onsaid main surface; (B2) forming a second conductive film on said fourthinsulating film; (B3) forming a fifth insulating film on said secondconductive film; (B4) patterning said second conductive film and saidfifth insulating film, thereby forming a second wiring and a secondupper insulating film covering an upper surface thereof; (B5) depositinga sixth insulating film to cover said main surface of said semiconductorsubstrate in such a thickness as to bury said second upper insulatingfilm therein; (B6) removing said sixth insulating film to leave, as asecond side wall, a portion covering side surfaces of said second wiringand said second upper insulating film; (B7) removing said fourthinsulating film to leave portions covered with said second wiring andsaid second side wall, simultaneously with said step (B6) or after saidstep (B6); and (B8) depositing said first conductor layer to cover saidmain surface of said semiconductor substrate in such a thickness as tobury said second upper insulating film therein; and said step (C)includes the step of: (C1) flattening said upper surface of said firstconductor layer to maintain such a configuration that said second upperinsulating film is buried.
 12. The method of manufacturing ahigh-frequency semiconductor device according to claim 10, wherein saidstep (B) includes the steps of: (B1) forming a fourth insulating film onsaid main surface; (B2) forming a second conductive film on said fourthinsulating film; (B3) forming a fifth insulating film on said secondconductive film; (B4) patterning said second conductive film and saidfifth insulating film, thereby forming a second wiring and a secondupper insulating film covering an upper surface thereof; (B5) depositinga sixth insulating film to cover said main surface of said semiconductorsubstrate in such a thickness as to bury said second upper insulatingfilm therein; (B6) removing said sixth insulating film to leave, as asecond side wall, a portion covering side surfaces of said second wiringand said second upper insulating film; (B7) removing said fourthinsulating film to leave portions covered with said second wiring andsaid second side wall, simultaneously with said step (B6) or after saidstep (B6); and (B8) depositing said first conductor layer to cover saidmain surface of said semiconductor substrate in such a thickness as tobury said second upper insulating film therein; and said step (C)includes the step of: (C1) flattening said upper surface of said firstconductor layer to maintain such a configuration that said second upperinsulating film is buried.
 13. The method of manufacturing ahigh-frequency semiconductor device according to claim 9, furthercomprising the steps of: (AA) selectively forming, in said firstinsulating film and said first conductor layer, a through holepenetrating from an upper surface of said first insulating film to alower surface of said first conductor layer, after said step (D) andbefore said step (E); (BB) forming a side insulating film covering aside wall surface of said through hole before said step (E); and (CC)forming a conductive plug to fill in said through hole with said sideinsulating film interposed therebetween before said step (E), said firstconductive film being also deposited on said through hole to beconnected to said conductive plug at said step (E), and said firstwiring being formed to be connected to said conductive plug by coveringsaid through hole at said step (G).
 14. The method of manufacturing ahigh-frequency semiconductor device according to claim 12, furthercomprising the steps of: (AA) depositing a second sacrificial layer tocover said main surface of said semiconductor substrate in such athickness as to bury said second upper insulating film therein, aftersaid step (B7) and before said step (B8); and (BB) patterning saidsecond sacrificial layer to leave a part thereof as a columnar portionbefore said step (BB), said first conductor layer being deposited tocover said main surface of said semiconductor substrate in such athickness as to bury said second upper insulating film therein at saidstep (B8), and an upper surface of said columnar portion and said uppersurface of said first conductor layer being flattened to maintain such aconfiguration that said second upper insulating film is buried at saidstep (Cl), and said method further comprising the steps of: (CC)removing said columnar portion, thereby forming a through hole in saidfirst conductor layer after said step (C1) and before said step (D);(DD) forming a side insulating film to cover a side wall surface of saidthrough hole after said step (CC) and before said step (D); and (EE)forming a conductive plug to fill in said through hole with said sideinsulating film interposed therebetween before said step (D), said step(D) including the steps of: (D1) forming said first insulating film onsaid upper surface of said first conductor layer which is flattened andover said through hole; and (D2) selectively removing said firstinsulating film such that at least a part of an upper surface of saidconductive plug is exposed, said first sacrificial layer being depositedon an exposed surface of said conductive plug as well as on said firstinsulating film at said step (E), said trench being formed such thatsaid exposed surface of said conductive plug is exposed at said step(F), and said conductive material being deposited to be connected tosaid exposed surface of said conductive plug at said step (G).
 15. Themethod of manufacturing a high-frequency semiconductor device accordingto claim 14, wherein at least an upper surface portion of said fifthinsulating film and said sixth insulating film are formed of the samematerial and said second sacrificial layer is formed of another materialdifferent therefrom.
 16. The method of manufacturing a high-frequencysemiconductor device according to claim 10, wherein at least an uppersurface portion of said second insulating film and said third insulatingfilm are formed of the same material.